PRESCOTT, Ariz. (AP) — They were fathers and expectant fathers. High school football players and former Marines. Smoke-eaters’ sons and first-generation firefighters.

What bound the members of the Granite Mountain Hotshots together was a “love of hard work and arduous adventure,” and a willingness to risk their lives to protect others. And now, 19 families share a bond of grief.

All but one of the Prescott-based crew’s 20 members died Sunday when a wind-whipped wildfire overran them on a mountainside northwest of Phoenix. It was the nation’s biggest loss of firefighters in a wildfire in 80 years and the deadliest single day for fire crews since the terror attacks of Sept. 11, 2001.

In the firefighting world, “Hotshot” is the name given to those willing to go to the hottest part of a blaze. They are the best of the best, crews filled with adventure-seekers whose hard training ready them for the worst.

“We are routinely exposed to extreme environmental conditions, long work hours, long travel hours and the most demanding of fireline tasks,” the group’s website says. “Comforts such as beds, showers and hot meals are not always common.”

Above all, the crew’s members prided themselves on their problem-solving, teamwork and “ability to make decisions in a stressful environment.”

“It’s a younger man’s game,” said Prescott Fire Chief Dan Fraijo, and the statistics bear him out. Of those who died, 14 were in their 20s; their average age was just 26.

At least three members of the crew were following in their fathers’ firefighting footsteps.

Kevin Woyjeck, 21, used to accompany his dad, Capt. Joe Woyjeck, to the Los Angeles County Fire Department, sometimes going on ride-alongs. The firehouse was like a second home to him, said Keith Mora, an inspector with that agency.

“He wanted to become a firefighter like his dad and hopefully work hand-in-hand,” Mora said Monday outside a fire station in Seal Beach, Calif., where the Woyjeck family lives. “He was a great kid. Unbelievable sense of humor, work ethic that was not parallel to many kids I’ve seen at that age. He wanted to work very hard.”

Chris MacKenzie, 30, grew up in California’s San Jacinto Valley, where father Michael was a former captain with the Moreno Valley Fire Department. An avid snowboarder, MacKenzie joined the U.S. Forest Service in 2004, then transferred two years ago to the Prescott Fire Department.

Dustin DeFord, 24, was a Baptist preacher’s son, but it was firefighting that captured his imagination.

At 18, he volunteered for the Carter County Rural Fire Department like his father did in his hometown of Ekalaka, Mont., according to The Billings Gazette. Almost everyone knew DeFord in the small town where he grew up and had worked a variety of jobs, the local sheriff said.

He liked to cliff jump and run “Spartan Race” obstacle courses, and he passed the physical test for the Granite Mountain crew in January 2012.

“He was one of the good ones who ever walked on this earth,” Carter County Sheriff Neil Kittelmann told the newspaper.

Many of those killed were graduates of Prescott High. One of them was 28-year-old Clayton Whitted, who as a firefighter would work out on the same campus where he played football for the Prescott Badgers from 2000 to 2004.

The school’s football coach, Lou Beneitone, said Whitted was the type of athlete who “worked his fanny off.”

“He wasn’t a big kid, and many times in the game, he was overpowered by big men, and he still got after it,” the coach said. “He knew, ‘This man in front of me is a lot bigger and stronger than me,’ but he’d try it, and he’d smile trying it.”

As a condition of hire, each of these Hotshot members was required to pass the U.S. Forest Service’s “Arduous Work Capacity Test” — which entails completing a 3-mile hike carrying a 45-pound pack in 45 minutes. The group also set for its members a fitness goal of a 1.5-mile run in 10 minutes, 35 seconds; 40 sit-ups in 60 seconds; 25 pushups in 60 seconds; and seven pull-ups, according to the crew’s website.

“The nature of our work requires us to endure physical hardships beyond most people’s experiences,” the website said. “Environmental extremes, long hours, bad food, and steep, rugged terrain, demand that we train early and often by running and hiking, doing core exercises, yoga, and weight training.”

The group started in 2002 as a fuels mitigation crew — clearing brush to starve a fire. Within six years, they had made their transition into the “elite” Hotshot community.

At Captain Crossfit, a warehouse filled with mats, obstacle courses, climbing walls and acrobatic rings near the firehouse where the Hotshots worked, trainers Janine Pereira and Tony Burris talked about their day-to-day experiences with the crew in what was a home away from home for most of them.

The whole group grew beards and mustaches before the fire season started but had to shave them for safety.

“They were trying to get away with it, and finally someone was like, ‘No. You’ve got to shave that beard,’” Pereira said. “They were the strongest, the happiest, always smiling.”

Former Marine Travis Turbyfill, 27, whose nickname was “Turby,” would come in to train in the morning, then return in the afternoon with his two daughters and wife, Stephanie, a nurse, Pereira said.

“He’d wear these tight shorts … just to be goofy,” Pereira said. “He was in the Marine Corps and he was a Hotshot, so he could wear those and no one would bug him.”

Andrew Ashcraft, 29, another Prescott High graduate, would bring his four children to the Captain Crossfit daycare, Pereira said.

“He’d come in in the early morning and do a workout, and then, to support his wife, he’d do one again,” she said. “He’d carry her around sometimes and give her a kiss in front of all his guys.”

Other members of the group were just beginning families.

Sean Misner, 26, leaves behind a wife who is seven months pregnant, said Mark Swanitz, principal of Santa Ynez Valley Union High School in Santa Barbara County, where Misner graduated in 2005. Marine Corps veteran Billy Warneke, 25, and his wife, Roxanne, were expecting their first child in December, his grandmother, Nancy Warneke, told The Press-Enterprise newspaper in Riverside.

At 43, crew superintendent Eric Marsh was by far the oldest member of the group. An avid mountain biker who grew up in the mountains of North Carolina, Marsh became hooked on firefighting while studying biology at Arizona State University, said Leanna Racquer, the ex-wife of Marsh’s cousin.

In April 2012, Marsh let reporters from the ASU Cronkite News Service observe one of the crew’s training sessions. That day, they were playing out the “nightmare scenario” — surrounded by flames, with nothing but a thin, reflective shelter between them and incineration.

“It’s not uncommon to have a rookie die,” Marsh told the news service. “Fake die, of course.”

On Monday, more than 1,000 people crowded into the bleachers and spilled onto the gymnasium floor at the Prescott campus of Embry-Riddle Aeronautical University. The crowd stood for more than a minute as firefighters in uniform walked in.

U.S. Rep. Matt Salmon said the Hotshots had made the ultimate sacrifice: “They gave their lives for their friends.”

“It’s times like today that define who we are,” he said.

When U.S. Rep. David Schweikert asked audience members to raise their hands if they knew one of the fallen firefighters, about a third of the crowd did.

In a shaking voice, Fire Chief Fraijo described a picnic he threw last month for his new recruits and their families. Earlier Monday, he met with those same families in another auditorium and gave them the tragic news.

“Those families lost,” he said. “The Prescott Fire Department lost. The city of Prescott lost. The state of Arizona and the nation lost.”